It is known that sound recordings can be reproduced on motion picture films or tapes by optoelectrical or magnetic means. Light beam and electrical signals representing the sound recordings to be reproduced are magnetically coupled onto the blank films or tapes in the forms of optical or magnetic tracks.
While these reproductive processes offer a quick and reliable way to reproduce sound recordings, they often require complicated and expensive equipment, thereby increasing the cost of production dramatically.
Accordingly, the technique using mechanical grooves has been proposed as an alternative for the sound recording reproduction process. It is recognized that sound recordings can be represented in the form of mechanical imprints on a film or tape and these imprints can be easily reproduced on blank films and tapes, especially when these films and tapes are made of plastic materials. This process requires relatively inexpensive and imprecise sound reproducing equipment and provides the reproduced films and tapes the advantage of being readable by simple needle pickups.
On the other hand, due to the structure and length of the films and tapes, the grooves must be imprinted individually, thereby imposing very restricting limitations on production speed even when several machines are incorporated to produce a certain number of recorded tapes simultaneously.